Characterization of Ba(Ti,Zr)O3 ceramics sintered under reducing conditions

Over the past few years, lead-free relaxor dielectrics have become particularly interesting for industrial applications. Due to the use of low cost base metal electrodes (BME), reductive sample sintering is required. This contribution refers to the influence of reducing sintering atmospheres on the dielectric behaviour of Mn-doped Ba(TixZr1-x)O-3 ceramics with different Zr-contents (x = 0-100 at.%). It was studied by impedance spectroscopy in the temperature range T = -150-300 degreesC and the frequency range f= 5 mHz-10 MHz. For the interpretation of the impedance spectra we used an equivalent electrical circuit to separate bulk from grain boundary or electrode contributions, respectively. It was found that reductive sintering decreases the maximum dielectric constant by approx. 20%. Further, a T-Curie, shift towards lower temperatures was observed, In contrast to materials sintered under oxidizing conditions, reduced sintered samples showed a plateau in the T-Curie versus Zr-content plot, derived from the Curie-Weiss behavior of the bulk in the cubic phase. (C) 2003 Elsevier Ltd. All rights reserved